FR3070294A1 - MULTI-DISTANCE DETECTION DEVICE FOR A ROBOT, AND ROBOT EQUIPPED WITH SUCH DEVICE (S) - Google Patents

Abstract

The invention relates to a device (100) for detecting objects for a robot, intended to equip said robot, comprising: at least one sensor (102), said approach, implementing a first detection technology to detect a surrounding object; at least one sensor (104,700), said contact, implementing a second detection technology to detect a surrounding object, different from said first technology, and range less than the range of said at least one approach sensor (102 ). It also relates to a robot equipped with such a device (100).

Description

"Multi-distance detection device for a robot, and robot equipped with such device (s)"

Technical area

The present invention relates to an object detection device for a robot. It also relates to a robot provided with such object detection device (s).

The field of the invention is, without limitation, that of the field of robotics, in particular the field of industrial robotics or service robots, for example medical or domestic, or even collaborative robots, also called “cobots ".

State of the art

Industrial or domestic robots, in particular cobots, generally comprise a body on which a functional head is fixed, being in the form of a tool or a tool holder, allowing them to accomplish one or more tasks.

To be able to use or develop a robot or co-bot, such as for example a robotic arm, in an environment comprising humans and / or objects, it is necessary to equip it with a detection capacity allowing on the one hand to avoid collisions with surrounding objects / humans and on the other hand to detect objects / humans early enough to be able to adapt its trajectory.

Sensors of small dimensions and low cost, such as capacitive sensors, are known for equipping a robot. These sensors have a short range and do not allow objects to be detected early enough to adapt the trajectory.

There are also known larger and more expensive sensors offering a greater detection range, such as time of flight sensors, optical sensors, etc. However, these sensors have a relatively small detection aperture, of the order of 60 ° maximum, leaving blind areas. To reduce these blind zones, it would be necessary to multiply the number of sensors, which is not possible considering

- 2 of the cost and size of these sensors. In addition, these sensors generally do not allow detection of objects at very short distance or in contact because of their measurement range.

Thus, due to the existence of blind zones and detection limits, these sensors are not well suited for collision avoidance security applications.

An object of the present invention is to provide a detection device for a robot offering better detection of objects, while presenting an acceptable cost and size.

Another object of the present invention is to provide a detection device for a robot having an acceptable cost and size and making it possible to carry out a detection of both near and far objects, with less, or even no, areas blind.

Another object of the present invention is to provide a detection device for a robot enabling object detection to be carried out in the vicinity of the robot with sufficient detection reliability to be able to be used as an anti-collision safety device.

Yet another object of the present invention is to provide a detection device for a robot allowing both trajectory adaptation and contact detection.

Statement of the invention

At least one of these aims is achieved with an object detection device for a robot, designed to equip said robot, comprising:

at least one sensor, called an approach sensor, implementing a first detection technology for detecting a surrounding object; and

at least one sensor, called a proximity sensor, implementing a second detection technology for detecting a surrounding object, different from said first technology, and with a range less than the range of said at least one approach sensor.

Thus, the detection device according to the invention proposes to perform object detection by a combination of two types of sensors offering different ranges.

- 3 Approach sensors, generally expensive and bulky, detect objects at a greater distance and allow trajectory adaptation. In combination with these approach sensors, proximity sensors of lower range are used to cover the blind areas not covered by the approach sensors, at a shorter distance, and allow contact detection, for example trigger an emergency stop or avoidance, or even change the robot's compliance or perform a touch command ...

Proximity sensors are less expensive and less bulky compared to approach sensors. Thus, the detection device allows better detection of objects, while presenting an acceptable cost and size. It allows trajectory adaptation and contact detection with very little, if not without, blind area.

Thus, the detection device according to the invention is compatible with the detection safety requirements required to be able to be used as an anti-collision safety device, in particular with respect to human operators operating in the vicinity of the robot.

In the present application, two alternative potentials are identical at a given frequency when they each comprise an alternative component identical to this frequency. Thus, at least one of the two potentials identical to said frequency may further comprise a DC component, and / or an AC component of frequency different from said given frequency.

Similarly, two alternative potentials are different at the working frequency when they do not include an alternative component identical to this working frequency.

In the present application, the term “ground potential” or “general ground potential” designates a reference potential of the electronics, the robot or its environment, which can for example be an electrical ground or a ground potential. This ground potential can correspond to a ground potential, or to another potential connected or not to the ground potential.

It is also recalled that in general, objects which are not in direct electrical contact with a particular electrical potential (objects

- 4 electrically floating) tend to polarize by capacitive coupling to the electrical potential of other objects present in their environment, such as for example earth or electrodes, if the overlapping surfaces between these objects and those of the environment (or the electrodes) are large enough.

In the present request, “object” designates any object or person that may be in the environment of the robot.

By “robot” is meant any robotic system, and in particular a robotic arm, a vehicle on wheels such as a trolley provided with an arm or a manipulating system, or a robot of the humanoid type or provided with organs. traveling such as limbs.

According to an advantageous characteristic, at least one approach sensor can perform an object detection up to a distance at least equal to 30cm, in particular up to a distance at least equal to 50cm.

Depending on the technologies used, an approach sensor can for example detect an object at distances between a minimum distance of a few centimeters and a maximum distance of a few tens of centimeters, or a few meters. In general, the detection of an object or at least the measurement of its distance is not possible below the minimum distance.

Thus, the approach sensor can detect an object when it is relatively far from the robot, which gives the robot time to modify / adjust its trajectory in order to avoid said object, while continuing to perform the task that it is performing, for example.

According to another advantageous characteristic, at least one approach sensor can carry out detection at a frequency at least equal to 10 Hz. Ideally, an approach sensor can perform detection up to a frequency of 100Hz, or more.

Such a measurement frequency for detecting an object, when the latter is far from the robot, is sufficient to adjust / modify the trajectory of the robot.

- 5 According to the invention, at least one approach sensor can be formed by any of the following sensors:

- a time-of-flight sensor or a rangefinder, optical or acoustic,

- a time-of-flight camera (3D),

- a stereoscopic and / or structured light projection optical device, or

- an optical imaging device.

Thus, by way of nonlimiting examples, the approach sensors can include:

- time of flight ultrasonic sensors (SODAR). These sensors have a centimeter resolution and can measure distances to objects present in a detection cone in the axis of the sensor (for example of 50 degrees of angle), between a minimum distance (for example 20cm) and a maximum distance (for example of lm or more);

- time of flight optical sensors (LIDAR). These sensors also have a centimeter resolution and can measure distances to objects present in a detection cone in the axis of the sensor (for example from a few degrees to a few tens of degrees of angle), between a minimum distance (for example 10cm) and a maximum distance (which can be of the order of several meters);

- time-of-flight cameras which apply the same optical principle of time-of-flight detection with an imaging sensor. These sensors can measure distances to objects present in a field of view along the axis of the sensor (for example a few tens of degrees of angle), between a minimum distance (for example 50cm) and a maximum distance (which can be of the order of several meters);

- optical sensors which use a structured light projection, or sensors based on stereovision. These two sensor principles have in common that they make it possible to measure a distance to an object present in an area of intersection between either an illumination beam and a field of view, or two fields of view;

- imaging sensors, which make it possible by segmenting images to identify the presence of an object in their field of view.

Advantageously, at least one proximity sensor can detect an object up to a distance at least equal to 10 cm, or ideally 20 cm or 30 cm.

Thus, the at least one proximity sensor can detect an object when it is in contact with the sensor, or at a distance of up to at least 10 cm, or ideally at least 20cm or 30cm. Thus, the proximity sensor presents a range of complementary distance measurements, as well as a reduced bulk and a reduced cost, compared to the approach sensors.

In addition, at least one proximity sensor can perform detection at a frequency at least equal to 100 Hz, or ideally at least equal to 500 Hz or 1000 Hz.

Such a measurement frequency is particularly suitable for detecting objects very close to the robot, while leaving sufficient time for the robot to stop before colliding.

This measurement frequency is sufficient to ensure anti-collision safety for a robot while using proximity sensors of acceptable cost and size.

According to a particularly preferred embodiment, at least one, in particular each, proximity sensor can be a capacitive sensor comprising at least one measurement electrode polarized at a first alternating electrical potential different from a general ground potential, at a frequency of work.

Capacitive sensors are particularly suitable for detecting objects at a short distance (less than 20-30cm), or in contact, with a measurement frequency sufficient to ensure anti-collision safety, while presenting a very reduced cost and size. . In addition, equipping a robot with capacitive sensors can be carried out quickly, simply and without, or with very little, modification of the architecture of the robot.

- 7 In this preferred embodiment, the detection device can comprise an electrode, or a surface, called a guard, for keeping at least one measurement electrode, and polarized at an alternating electric potential (V _G ), said a guard , identical or substantially identical to the first alternating electrical potential, at the working frequency.

Such a guard electrode makes it possible to protect the capacitive measurement electrode from external disturbances, such as leakage capacities, and thus to increase the range and the accuracy of the measurement electrode.

Still, in this preferred embodiment, at least one, in particular each, approach sensor can preferably be referenced to the guard potential (V _G ). Thus, the or each approach sensor is not detected by the measurement electrode (s), and does not interfere with the detection.

To do this, the device according to the invention can comprise at least one electrical converter arranged for:

- receiving at least one electrical signal, called the input signal, such as a supply or control signal referenced for example to a ground potential and intended for at least one approach sensor, and referencing said input signal the guard potential (V _G ); and or

- receiving at least one electrical signal, called the output signal, emitted by the at least one approach sensor, and referencing the said output signal to the electrical ground potential of a controller for which it is intended.

Thus, the approach sensor of the device according to the invention is generally referenced to the guard potential and therefore does not disturb the capacitive sensors.

According to exemplary embodiments, such an electrical converter can comprise at least one of the following elements:

- at least one galvanically isolated power supply, such as a DC / DC converter, in particular for generating a power input signal for at least one approach sensor;

- at least one electrical interface without galvanic contact, of the capacitive type or by optocoupler, for at least one control input signal, or at least one output signal; and or

- one or more high impedance inductors to receive and transmit at least one input signal or at least one output signal.

Advantageously, at least one, or a set of several, proximity sensor (s) can be positioned between at least two approach sensors so that its detection area covers an area not covered by said approach sensors, and this in at least one direction, and in particular in the direction connecting said two approach sensors together.

In particular, if the area covered by the approach sensors has a truncated conical shape, with an opening angle and a minimum detection distance, the proximity sensor or sensors can advantageously be positioned between the approach sensors. so that their detection zones cover an area between the areas covered by the approach sensors, and / or between these covered areas and the corresponding approach sensors.

Thus, the detection device according to the invention makes it possible to cover more space during the detection of objects and to reduce the blind zones.

In addition, at least one approach sensor can be positioned so that its detection zone overlaps, at least partially, with a detection zone of one, or a set of several, proximity sensor (s). , and this in at least one direction, and in particular in the direction connecting said contact and approach sensor (s).

In this embodiment, there is no blind zone between an approach sensor and a proximity sensor, which further improves the detection of objects by the device according to the invention.

Preferably, at least two approach sensors can be positioned so that their detection zones overlap, at least partially between them.

- 9 At least two approach sensors can also be positioned so that:

their detection zones overlap each other, for example beyond an overlap distance, and

- the common part of their detection zones overlaps with a detection zone of one, or a set of several, proximity sensor (s);

and this in at least one direction, in particular in the direction connecting said two approach sensors.

In this embodiment, there is no blind zone between the approach sensors, or at least no blind zone beyond the overlap distance if applicable.

According to another aspect of the same invention, there is provided a covering element for a robot equipped with at least one detection device according to the invention.

Such a covering element may be in the form of a flexible covering forming a skin.

Such a covering element may be in the form of a flexible or rigid shell.

Such a covering element can be used in place of an existing covering element of a robot.

Such a covering element can be used in addition to an existing covering element of a robot. In this case, the covering element according to the invention can be arranged on said existing covering element, in the form of a lining element or a second shell, or even of a coating.

According to yet another aspect of the present invention, there is provided a robot equipped:

at least one detection device according to the invention; and or

- 10 - of a covering element according to the invention, in addition to or in place of an existing covering element.

The robot according to the invention can comprise, for at least one segment of said robot:

a plurality of proximity sensors distributed on said segment of the robot, and

- A plurality of approach sensors, for example arranged at at least one, and in particular at each of the ends of said segment.

The robot according to the invention can be equipped with a functional head, forming a tool or a tool holder.

In a non-limiting embodiment, said functional head can be used as a capacitive detection electrode, or a measurement electrode. To do this, the functional head is isolated from the rest of the robot and polarized at the first alternating potential. The functional head can be isolated from the rest of the robot by an insulating surface inserted between said functional head and the rest of the robot.

In this case, the functional head can also be equipped with at least one approach sensor, in particular several approach sensors arranged on either side of said functional, for example in the form of a ring .

Optionally, a guard surface, polarized at the guard potential (V _G ), can be provided to keep said functional head used as a capacitive electrode. Such a guard surface can be inserted between said functional head and the rest of the robot, while being isolated both from the functional head and from the rest of the robot.

According to another aspect of the same invention, there is proposed a trajectory control method for a robot according to the invention, said method comprising a step of generating, or modifying, a trajectory of at least a part of said robot depending

- at least one signal supplied by at least one approach sensor, and

- at least one signal supplied by at least one proximity sensor.

When the object is detected by an approach sensor without being detected by a proximity sensor, this means that the object is far enough to avoid it. In this case, the trajectory of the robot (or of a mobile head of the robot) is generated / modified globally, and / or in an optimized manner, to avoid said object.

When the object is detected by a proximity sensor, this means that the object is very close to the robot and that there is more time to avoid it. In this case, the trajectory of the robot is modified to cause the robot to stop, or avoidance at short distance.

Description of the figures and embodiments

Other advantages and characteristics will appear on examining the detailed description of nonlimiting examples, and the appended drawings in which:

- FIGURES 1 and 2 are schematic representations of two non-limiting examples of the principle of a detection device according to the invention;

- FIGURE 3 is a schematic representation of a nonlimiting exemplary embodiment of a robot equipped with two detection devices according to the invention;

- FIGURE 4 is a schematic representation, in section, of a detection device fitted to the robot of FIGURE 3;

- FIGURES 5 and 6 are schematic representations of two examples of electronics that can be implemented in a detection device according to the invention; and

- FIGURE 7 is a schematic representation of a nonlimiting exemplary embodiment of a functional head which can equip a robot according to the invention.

It is understood that the embodiments which will be described below are in no way limiting. We can in particular imagine variants of the invention comprising only a selection of characteristics

- 12 described hereinafter isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, or with only a part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

In particular, all the variants and all the embodiments described can be combined with one another if there is nothing technically opposed to this combination.

In the figures, the elements common to several figures keep the same reference.

FIGURE 1 is a schematic representation of a non-limiting example of the principle of a detection device according to the invention.

The detection device 100 of FIGURE 1 comprises sensors 102, called approach, and sensors 104, called proximity.

In FIGURE 1, three approach sensors 102 and six proximity sensors 104 are shown, with three proximity sensors 104 between two consecutive approach sensors 102.

The approach sensors 102 have a greater detection range compared to that of the proximity sensors 104.

The approach sensors 102 can be selected from the following sensors:

- a time-of-flight sensor or a rangefinder, optical or acoustic,

- a time-of-flight camera (3D),

- a stereoscopic and / or structured light projection optical device, or

- an optical imaging device.

Of course, it is possible to use any combination of the sensors listed above so that the approach sensors are any combination of these sensors.

- 13 According to a preferred embodiment, the approach sensors 102 used can be time-of-flight (point) optical sensors.

The approach sensors 102 carry out an object detection up to a distance of at least 50 cm, or even more, up to a few meters. The detection frequency of these sensors is typically around a hundred Hertz.

Each approach sensor 102 has a cone-shaped detection zone, the apex of which is at the level of the approach sensor 102. The aperture angle of the cone of each approach sensor 102 is of the order of several tens of degrees, and in particular of the order of 50 ° or 60 °. Insofar as these approach sensors cannot detect objects at a distance less than a minimum distance (for example 10 cm), their detection zone has rather the shape of a truncated cone.

As seen in FIGURE 1, from a certain distance, the detection zones of two successive / adjacent approach sensors 102 overlap. However, there is also between two consecutive approach sensors 102, an area 106 not covered by the approach sensors 102. If an object is in this uncovered area 106, it is not detected by any approach 102.

Proximity sensors 104 perform detection of an object at a maximum distance of 25-30 cm. The detection frequency of these sensors is around 1000Hz.

As the proximity sensors 104 are positioned between the approach sensors 102, they detect objects located in the zones 106, which are not covered by the approach sensors 102.

In particular, in at least one direction:

the distance between two consecutive approach sensors 102, and

the number of proximity sensors 104 disposed between these two consecutive approach sensors 102;

are chosen such that the detection zone of the proximity sensors 104 covers the majority, and preferably all, of the zone 106, not covered by two consecutive approach sensors 102.

- 14 In the example shown in FIGURE 1, each proximity sensor 104 is formed by a capacitive electrode, hereinafter called the measurement electrode.

Each measurement electrode 104 is designed to be biased at a first alternating electrical potential, different from a ground potential, at a working frequency. The detection of an object is carried out by measuring a signal relating to the capacity, called the electrode-object, seen by each measurement electrode. This detection principle is well known and will therefore not be detailed here.

In addition, to avoid leakage capacitances or parasitic capacitances which could constitute a disturbance, each measurement electrode 104 is kept at an alternating electrical potential, known as a guard, denoted V _G , identical to the first alternating potential, at the working frequency. . To do this, the detection device 100 comprises a guard electrode 108, forming a guard plane, and common to all the measurement electrodes 104.

According to an alternative embodiment, it is possible to use an individual guard electrode for each measurement electrode 104.

In the example shown in FIGURE 1, there is a zone 110 at the level of which the detection zones overlap:

- two consecutive approach sensors 102, and

proximity sensors 104 arranged between these two consecutive approach sensors 102.

Thus, there is no blind zone in which an object close to the detection device is not detected.

FIGURE 2 is a schematic representation of another non-limiting example of the principle of a detection device according to the invention.

The device 200 includes all the elements of the device 100 of FIGURE 1, with the difference that there are only two proximity sensors 104, or measurement electrodes 104, between two consecutive approach sensors 102.

Therefore, as shown in FIGURE 2, the detection zone of the proximity sensors 104 is smaller, and covers the majority of the uncovered zone 106 between two consecutive approach sensors 102, but

- not all of this area 106. In particular, the detection zone of the proximity sensors 104 does not overlap with the zone of overlap of two consecutive approach sensors 102.

Consequently, there is a small blind area 202 between two consecutive approach sensors 102 in which an object is not detected.

Of course, the device 200 is less effective in detection than the device 100 of FIGURE 1, while remaining sufficiently functional.

Detection electronics are associated with the detection device. Examples of detection electronics will be described below with reference to FIGURES 5 and 6.

FIGURE 3 is a partial schematic representation of a nonlimiting exemplary embodiment of a robot according to the invention.

The robot 300, shown in FIGURE 3, is in the form of a robotic arm comprising several articulations connecting together several segments. Each joint makes it possible to rotate around an axis of rotation.

The robot 300 is equipped with two detection devices 302 and 304 according to the invention. Each detection device 302 and 304 can, for example, be produced according to the principle described with reference to FIGURE 1 or to FIGURE 2.

As shown in FIGURE 3, each detection device 302 and 304 is in the form of a covering element, such as a cover or a skin or also a trim element, coming to be positioned above d '' an existing robot cover. Of course, according to an alternative embodiment, each detection device can be integrated into / on an existing covering element of the robot.

The detection device 302 is in the form of a cylinder comprising at each of its ends a ring of approach sensors 102 comprising four equidistant approach sensors 102. The detection device 302 also includes a multitude of proximity sensors 104 distributed over the entire surface of the cylinder and between the approach sensors 102.

- 16 The detection device 304 is in the form of an annular band, or a bracelet, comprising a ring of approach sensors 102 comprising four equidistant approach sensors 102. The detection device 304 also includes three proximity sensors 104 between two successive approach sensors 102.

Of course, the number and the position of the sensors are not limiting.

FIGURE 4 is a schematic representation, in section, of a detection device fitted to the robot 300 of FIGURE 3.

The device shown in FIGURE 4 can be any of the devices 302 or 304 in FIGURE 3.

As shown in FIGURE 4, the detection zones of two successive approach sensors 102 do not overlap. Part of the uncovered area located between two successive approach sensors 102 is covered by the proximity sensors 104 located between these approach sensors.

We also note that the detection range of proximity sensors 104 is much smaller than that of approach sensors 102.

FIGURE 5 is a schematic representation of an example of electronics that can be implemented in / with a detection device according to the invention.

The electronics 500 shown in FIGURE 5 can be implemented with the device 100, 200, 302 or 304 of FIGURES 1-4.

In the example shown in FIGURE 5, the electronics 500 comprises an oscillator 502, referenced to a general ground 504, which generates an alternating excitation voltage, denoted V _G , used to polarize each measurement electrode 104, acting proximity sensor, and also used as a guard potential to polarize the guard electrode 108.

The electronics 500 comprises a detection electronics 506 composed of a current or charge amplifier, represented by a

- 17 operational amplifier 508 and a feedback capacity 510. In the embodiment presented, this charge amplifier supplies at the output a voltage proportional to the coupling capacity between the measurement electrode and a nearby object.

The detection electronics 506 further comprises a conditioner 512 making it possible to obtain a signal representative of the coupling capacity C _eo sought, and / or of the presence or proximity of an object of a body. This conditioner 512 can for example comprise a synchronous demodulator for demodulating the signal with respect to a carrier, at a working frequency. The conditioner 512 can also include an asynchronous demodulator or an amplitude detector. This conditioner 512 can of course be produced in analog and / or digital form (microprocessor) and include any necessary means of filtering, conversion, processing, etc.

In the configuration shown in FIGURE 5, each measurement electrode 104 is polarized via the operational amplifier 508. In particular, the oscillator 502 is connected to the positive input of the operational amplifier 508 and the measuring electrode is connected to the negative input of the operational amplifier 508.

The guard plane formed by the guard electrode 108 is connected to the negative input of the operational amplifier 508.

The detection electronics 500, or at least its sensitive part with the charge amplifier 506 can be referenced (or supplied by referenced electrical supplies) at the guard potential V _G , to minimize the parasitic capacitances.

The detection electronics 500 can also be referenced, more conventionally, to the ground potential 504.

The approach sensors 102 of the detection device are supplied / controlled by a controller 514. This controller 514 delivers signals (supply or control) referenced to the general ground potential 504, different from the guard potential V _G.

Without precautions, such signals, and consequently the approach sensors 102 could trigger an untimely detection on the part of

- 18 measuring electrodes 104 used as a proximity sensor, due to the presence of the ground potential.

To avoid this, the electronics of the detection device comprises a converter 516 placed between the controller 514 and the approach sensor 102 and having the function of:

- receive at least one electrical signal, called the input signal, such as a power supply or control signal, emitted by the controller 514 and intended for the approach sensor 102, and reference the said input signal at the guard potential V _G ; and

- receiving at least one electrical signal, called the output signal, emitted by said approach sensor 102 and intended for the controller 514, and referencing said output signal to the electrical ground potential 504 of said controller 514.

Thus, each approach sensor, as well as the connectors and the electronics associated with it, are supplied by signals referenced to the guard potential V _G and do not disturb the measurement electrode 104.

FIGURE 6 is a schematic representation of another example of electronics that can be implemented in / with a detection device according to the invention.

The electronics 600, shown in FIGURE 6, can be implemented with the device 100, 200, 302 or 304 of FIGURES 1-4.

Electronics 600 includes all of the electronics 500 in FIGURE 5.

The electronics 600 furthermore comprises a scanning means 602, which may for example be a switch, making it possible to connect, in turn, each measurement electrode 104 to the detection electronics 506. This architecture has the advantage of '' use detection electronics common to several measurement electrodes.

Of course, the electronics 500, 600 may also include scanning means (not shown) for controlling and / or interrogating approach sensors 102 sequentially.

- 19 FIGURE 7 is a schematic representation of a nonlimiting exemplary embodiment of a functional head which can be implemented in a robot according to the invention.

The functional head 700, shown in FIGURE 7, is in the form of a tool or a tool holder. In particular, the functional head 700 is a motorized gripper.

The functional head 700 comprises, or is associated with, a separation interface 702, which separates it from the rest of the robot. This separation interface 702 comprises at least one electrical insulator 704 which electrically isolates the functional head 700 from the rest of the robot.

Optionally, the separation interface 702 comprises a guard plane formed by a conductive plate 706, separated from the functional head 700 by the insulator 704, and separated from the rest of the robot by a second insulator 708.

The conductive plate 706 is biased at the guard potential V _G. The functional head 700, for its part, is biased at the first alternating electric potential which is identical to the guard potential V _G.

Under these conditions, the functional head 700 behaves like a capacitive electrode, or a measurement electrode, in the same way as the measurement electrodes 104 of FIGURES 1-4. Consequently, the functional head 700 can be used as a proximity sensor, in the same way as each measuring electrode 104.

In addition, the functional head 700 includes one or more approach sensors 102. In FIGURE 7, two approach sensors 102 are visible. Thus, the functional head 700 can be used as a detection device according to the invention for carrying out object detection in the same way as the detection devices 100, 200, 302 and 304 of FIGURES 1-4. The approach sensors 102 of the functional head 700 carry out a detection of an object when it is far from the functional head 700, and the rest of the functional head 700 carries out a detection of an object when it is close of the functional head 700, and in particular, in an area not covered by the approach sensors 102.

The approach sensors 102 are particularly useful with a functional head 700 used as a capacitive electrode because they provide a

- 20 information of the direction in which an object arrives, which is not provided by the capacitive electrode in this case. Thus, if the object is detected by an approach sensor 102, an avoidance trajectory can be carried out. On the other hand, if the object approaches in an area which is not covered by the approach sensors 102, it is nevertheless detected by the capacitive electrode in time to stop the robot and avoid a collision.

The signals exchanged with the approach sensors 102 equipping the functional head can be converted using a potential converter, such as for example the potential converter 516 of FIGURES 5 and 6. Thus, the approach sensors 102 do not interfere with the capacitive detection carried out by the functional head 700 or another measurement electrode 104 equipping the robot.

In addition, when the functional head 700 comprises an electrical member, such as for example an electric motor or other sensors, the signals exchanged with said electrical member can be converted using a potential converter, such as by example the potential converter 516 of FIGS. 5 and 6, in a similar or identical manner to the approach sensors 102. Thus, this electrical member does not interfere with the capacitive detection carried out by the functional head 700 or another measurement electrode 104 equipping the robot.

Of course, the invention is not limited to the examples which have just been described and numerous modifications can be made to these examples without departing from the scope of the invention.

Claims (15)

1. Device (100; 200; 300,304) for detecting objects for a robot (300), designed to equip said robot (300), comprising: at least one sensor (102), called an approach sensor, implementing a first detection technology for detecting a surrounding object; and at least one sensor (104,700), called a proximity sensor, implementing a second detection technology for detecting a surrounding object, different from said first technology, and of range less than the range of said at least one approach sensor (102 ). 2. Device (100; 200; 300,304) according to claim 1, characterized in that at least one approach sensor (102) detects an object up to a distance at least equal to 30cm, in particular up to a distance of at least 50cm. 3. Device (100; 200; 300,304) according to any one of the preceding claims, characterized in that at least one approach sensor (102) is formed by: - a time-of-flight sensor or a rangefinder, optical or acoustic, - a time-of-flight camera (3D), - a stereoscopic and / or structured light projection optical device, or - an optical imaging device. 4. Device (100; 200; 300,304) according to any one of the preceding claims, characterized in that at least one proximity sensor (104,700) detects an object up to a distance at least equal to 10 cm. 5. Device (100; 200; 300,304) according to any one of the preceding claims, characterized in that at least one proximity sensor (104,700) is a capacitive sensor comprising at least one measuring electrode (104,700) polarized at a first alternative electrical potential different from a general ground potential (504), at a working frequency. 6. Device (100; 200; 300,304) according to the preceding claim, characterized in that it comprises an electrode (108,706), or a surface, called a guard, for keeping at least one measuring electrode (104,700), and polarized at an alternating electrical potential (V _G ), called the guard potential, identical or substantially identical to the first potential, at the working frequency. 7. Device (100; 200; 300,304) according to any one of claims 5 or 6, characterized in that at least one, in particular each, approach sensor (102) is referenced to an alternating electric potential (V _G ), said to be on call, identical or substantially identical to the first potential, at the working frequency. 8. Device (100; 200; 300,304) according to any one of the preceding claims, characterized in that at least one, or a set of several, proximity sensor (s) (104) is positioned between at least two sensors approach (102) so that its detection area covers an area not covered by said approach sensors (102). 9. Device (100; 200; 300,304) according to any one of the preceding claims, characterized in that at least one approach sensor (102) is positioned so that its detection zone overlaps, at least partially, with a detection zone for one, or a set of several, proximity sensor (s) (104). 10. Device (100; 200; 300,304) according to any one of the preceding claims, characterized in that at least two approach sensors (102) are positioned so that their detection zones overlap, at least partially, between them. 11. covering element for robot equipped with at least one detection device (100; 200; 300,304) according to any one of the preceding claims. 12. Robot (300) equipped: -at least one detection device (302,304) according to any one of claims 1 to 10; and or - a covering element according to claim 11. 13. Robot (300) according to the preceding claim, characterized in that it comprises, for at least one segment of said robot: a plurality of proximity sensors (102) distributed over said segment of the robot, and - A plurality of approach sensors (104) arranged at at least one, in particular of each of the ends of said segment. 14. Robot (300) according to any one of claims 12 or 13, characterized in that it comprises a functional head (700), forming a tool or a tool holder, used as a capacitive detection electrode, said functional head (700): -forming a capacitive proximity sensor, and -comprising at least one approach sensor (102), in particular several approach sensors (102) arranged on either side of said functional (700). 15. Method of trajectory control for a robot (300) according to any one of claims 12 to 14 comprising a step of generation, or modification, of a trajectory of at least a part of said robot in function -at least one signal supplied by at least one approach sensor (102), - at least one signal supplied by at least one proximity sensor (104).